ROBERT MALLEY is President and CEO of the International Crisis Group. During the Obama administration, he served as Special Assistant to the President, White House Middle East Coordinator, and Senior Adviser on countering the Islamic State.

JON FINERserved as Chief of Staff and Director of Policy Planning at the U.S. Department of State during the Obama administration.

When it comes to political orientation, worldview, life experience, and temperament, the past three presidents of the United States could hardly be more different. Yet each ended up devoting much of his tenure to the same goal: countering terrorism[1].

Upon entering office, President George W. Bush initially downplayed the terrorist threat, casting aside warnings from the outgoing administration about al Qaeda plots. But in the wake of the 9/11 attacks, his presidency came to be defined by what his administration termed “the global war on terrorism,” an undertaking that involved the torture of detainees, the incarceration of suspects in “black sites” and at a prison camp in Guantánamo Bay, the warrantless surveillance of U.S. citizens, and prolonged and costly military campaigns in Afghanistan and Iraq.

Barack Obama’s[2] political rise was fueled by his early opposition to Bush’s excesses. He was clear-eyed about the nature of the terrorist threat and aware of the risks of overstating its costs. Once in office, he established clearer guidelines for the use of force and increased transparency about civilian casualties. But he also expanded the fight against terrorists[3] to new theaters, dramatically increased the use of drone strikes, and devoted the later years of his presidency to the struggle against the Islamic State (also known as ISIS).

As for Donald Trump, he helped incite a wave of fear about terrorism and then rode it to an unlikely electoral victory, vowing to ban Muslims from entering the United States and to ruthlessly target terrorists wherever they were found. In office, Trump has escalated counterterrorism operations around the world, significantly loosened the rules of engagement, and continued to play up the terrorist threat with alarmist rhetoric.

In short, in an era of persistent political polarization, countering terrorism has become the area of greatest bipartisan consensus. Not since Democrats and Republicans rallied around containing the Soviet Union during the Cold War has there been such broad agreement on a foreign policy priority. Counterterrorism was a paramount